Gear pump or motor with radial pressure balancing means



.1. 1.. NAGELY 3,029,739

GEAR PUMP OR MOTOR WITH RADIAL PRESSURE BALANCING MEANS April 17, 1962 5Sheets-Sheet 1 Filed July 9, 1958 u gimlzy g April 17, 1962 J. L. NAGELY3,029,739

GEAR PUMP OR MOTOR WITH RADIAL PRESSURE BALANCING MEANS Filed July 9,1958 5 Sheets-Sheet 2 April 1952 J. L. NAGELY 3,029,739

GEAR PUMP OR MOTOR WITH RADIAL PRESSURE BALANCING MEANS Filed July 9,1958 5 Sheets-Sheet 3 J23 7 I 150 1& rig

1 2 INVENTOR. 177 1 1 178 179 Z 2 140 Lfohnlz 140 17g 150' J50 J57 BY164 152 g '5.

April 17, 1962 J. NAGELY 3,029,739

GEAR PUMP OR MOTOR WITH RADIAL PRESSURE BALANCING MEANS Filed July 9,1958 5 Sheets-Sheet 4 iinited States This invention relates toimprovements in high pressure gear-type liquid displacement devices suchas bydraulic umps or motors. More particularly, the invention relates toa radial pressure balancing arrangement for a gear-type liquiddisplacement device employing an internal unit assembly construction.

One of the problems present in the high pressure gear 7 pump art hasbeen that of counterbalancing the effects of the discharge pressureforce at the high pressure side of the pump, particularly the axial andradial components of this force, which tend to axially separate theadjacent bushings or end plates from the side faces of the gears.

In my prior United StatesPatents No. 2,772,638, issued December4 1956,and No. 2,848,953, issued August 26,

1 958, I have disclosed andclaimed a novel high pressure gear pumpemploying an internal unit assembly type construction in which the gearsthereof .are supported and rotatably journalled in a pair of adjacentspaced end plates, the internal unit assembly including thrust bearingmeans cooperating with the end plates to provide annular annular axialpressure loading chambers for counterbalancing the axial component ofthe discharge pressure force tending to separate the end plates from theside faces of the gears, the reaction forces from the pressure loadingbeing taken up by the gear shafts or by separate tension members so thatthe axial forces are all resolved within the internal unit assemblyindependently of the pump casing. However, the pressure ditferentialexisting across the gears from the discharge side to the suction side ofthe pump results in a radial force component acting on the internal unitassembly as a free body and tending to displace the assembly bodilytoward the suction side so as to create substantial frictional forcesbetween the edges .of the end plates of the pump and the casing bore atthe suction or low pressure side. Such axial frictional forces tend toinfluence or interfere with proper posi-.

tioning of the end plates relative to the gear faces and the thrustbearing means so that "the axial counterbalancing force required tomaintain the end plates engaged with the side faces of the gears arevariable and oftentimes quite large. The present invention providesasirnple and effective means for counterbalancing this radial forcecomponent tending to urge the internal unit assembly into frictionalcontact with the suction side of the casing bore.

Although the invention hereinafter to be described is primarily suitedfor use in high pressure gear-type pumps employing an internal unitassembly construction, it will be understood that the principlesinvolved are applicable to liquid displacement devices generally,including both hydraulic pumps and motors.

Accordingly, a primary object of my invention is to provide a novelradial pressure balancing system for a liquid displacement device of theabove-described type.

Another object of the invention is to provide a novel radial pressurebalancing system for counterbalancing the radial force component of thedischarge pressure force in a liquid displacement pump of the typepreviously described to thereby maintain the liquid displacementelements of the pump in their prescribed reference position in order toobtain maximum pump efficiency.

A further object of the invention is to provide a novel radial pressurebalancing system for counterbalancing the radial force component of thedischarge pressure force at the high pressure zone in a positivedisplacement atent 3,d29,739 Patented Apr. 17, 1962 pump employing aninternal unitas'sembly construction in order to maintain a minimumclearancerel-ationship between the internal unit assembly and easingbore on the dischargeside of the pump and thereby minimize leakagearound the internal unit assembly.

Still another object of the invention is to provide, in a high pressuregear pump employing axial pressure loading chambers and an internal unitassembly construction, a novel radial pressure balancing system forcounterbalancing the radial force component of the discharge pressurewhich tends to urge the edges of the end plates of the internal unitassembly into frictional contact with the pump casing bore at thesuction side, thereby to minimize such frictional contact and reduce theaxial countcrbalancing force required to counterbalance the axialcomponent of the discharge pressure force tending to separate theendplates from the side faces of the gears.

Other objects and advantages of the invention will become evident fromthe following detailed description taken in connection with theaccompanying drawings, in which: V

FiGQl is a longitudinal sectional view, with some parts in elevation,showing a gear-type liquid displacement device that. employs an internalunit assembly construction and radial pressure balancing meanscomprising one specific embodiment of my invention;

FIG. 2 is'a reduced scale perspect ve view of the internal unit assemblyof the liquid displacement device I illustrated in FIG. l and showinggraphically the various forces acting on the internal unit assembly as afree body;

FIG. 3 is a sectional View taken along the line 3-3 of FIG. 1.;

FIG. 4 is a view similar to FIG. 3, taken along the line 4-4 of FIG. 1;

, pump casing;

.FIG. 7 is a side elevational view of an'end plate of an internal unitassembly comprisin'g another specific embodiment of the invention;

FIG. 8 is a cross-sectional view along the line 3-8 of FIG. 7 butshowing the end plate in assembledrelation in the pump casing; g Y

FIG. 9 is an elevational view as seen along the line 9-9 of FIG. 7;, IFIG. 10 is a side elevational view of still another end plate embodyinganother form of the invention;

FIG. '11 isa sectional view along the line 11-11 of FIG. 10 but showingthe end plate in assembled relation in the pump casing; y 7

FIG. 12 is an elevational view as seen along the line 12-12 of FIG. 10;

FIG. 13 is a side elevational view of an internal unit assemblycomprising another embodiment of the invent 7. j v

FIG. "14 is an end el-evational view of the internal unit assembly ofFIG. 13 as seen along the line 14-14 thereof; FIG. 15 is a'sec'tion'alview taken along the line 15-15 of-FIG. 13; y Y H FlG. 16 is .asectional view along the line 16-16 of FIG. 15; y y FIG. 17 is afragmentary sectional view taken along the line 17-17 of FIG. 13; I

FIG. 18 is an end elevational view of another internal unit assemblycomprising another specific embodiment of the invention; 7 I

FIG 19 is a sectional view taken along the line 19-19 of FIG. 18;

1G. 5 is a side elevational view of an end plateof.

FIG. is a side elevational view of the internal unit assembly of FIG.18, and with a portion thereof broken away to show a structural detail;

FIG. 21 is a transverse sectional view taken along the line 21-'21 ofFIG. 20;

FIG. 22 is a sectional view taken along the line 22-22 of FIG. 18;

FIG. 23 is' a sectional view taken along the line 23-23 of FIG. 19;

FIG. 24 is a sectional view taken along the line 24-24 of FIG. 22; and

FIG. 25 isa fragmentary sectional view taken along the line 25-25 ofFIG. 24.

Briefly described, my invention comprises a novel radial pressurebalancing system wherein high pressure working liquid is directed to oneor more confined chambers or zones on the low pressure side of a liquiddisplacement device, such that the reaction force provided by highpressure liquid in these chambers counterbalances the radial displacingcomponent on the high pressure side of the device. My invention isparticularly suited for use in liquid displacement devices of the typeemploying an internal unit assembly construction having a pair ofaxially shiftable end plates disposed on the opposite side faces of thegears for rotatably journalling the shaft portions of the gearsand whichutilizes one or more pairs of axial pressure loading chambers disposedadjacent the outer end faces of the end plates for counterbalanciug theaxial force component of the discharge pressure force tending toseparate the end plates from the gear'faces, such a system beingdescribed and claimed in my United States Patents No. 2,772,638, issuedDecember 4, 1956, and No.

4 portion 32 and also by a plurality of elongated screws 41 extendingthrough bores in the rear cover 38 and body portion 32 threaded into theopposite front cover 36. The construction of the driving and sealingmeans 37 at the drive end of the pump is conventional and furtherdescription thereof has therefore been omitted.

The internal unit assembly 31 generally comprises a pair of liquiddisplacing elements such as a drive gear 42 and driven gear 43 (FIGS. '1a'nd2) carried integrally on gear shafts 44 and 46 (FIGS. 2 and 3),respectively, each having an axial bore 47 therethrough. The drive endof the gear shaft 44 adjacent the front cover 36 may carry an eX-tension formed with a drive spline 48 for engagement with acomplementary drive spline 50 in the driving means 37, though any othersuitable drive connection could be utilized for transmitting torque fromthe driving means 37 to the internal unit assembly 31. v

'In order to support the gears 42 and 43 in meshed relationship and tomaintain a pumping seal around the side faces of the gears, 21 pair ofend plates 49 are disposed at the opposite side faces of the meshedgears, each end plate having axial bores therethrough, constitutingbearing journals for the gear shafts 44 and 46. Encircling the outerends of the gear shafts 44 and 46 are annular sealed thrust bearingmeans 51 which define annular axial pressure loading chambers forreceiving workingliquid at pump discharge pressure -to urge the endplates inwardly toward the gears '42 and 43 and to counterbalance thehydraulic pressure forces at the discharge side of the pump tending toseparate the end plates 49 from the side faces of the gears 42 and 43.Lubrication of the gear shaft journals, indicated generally at 52 inFIGS. 3 and 4, is provided by a pair of diametrically spaced axiallyextending grooves 53 which register with apair of annular grooves 54 inthe maintaining the internal unit assembly substantially centralized inits casing bore so that the frictional forces beunit assemblyconstructions, each of which comprises an exemplary embodiment of thepresent invention, As will hereinafter be more fully described, one 'ormore radial 1 pressure balancing chambers are disposed between theinternal unit assembly and the pump casing on the low pressure sidethereof, the chambers beingso located and having combined effectiveareas such that high pressure working liquid communicated to thechambers will effectively counterbalance the radial'component of thedischarge pressure and thus maintain the internal unit assemblycentralized in the pump casing as a free body.

Referring now to FIGS. 1-4 of the drawings, the invention will first bedescribed in connection with a geartype liquid displacement deviceemploying an internal unit assembly construction of the .type shown inmy aforementioned United States Patent No. 2,772,638, to which referencemay be made for further details of the structure and operation thereof.

The liquid displacement device illustrated in FIG. 1, and in thesucceeding figures, is-ofthe high pressure gear pump type and generallycomprises anexternal casing 30 and an internal unit assembly, indicatedat 31, which constitutes the operating mechanism of the pump and isreadily removable as a unit from the casing 30. The external casing 30generally includes a central body portion 32 having a liquid inlet port33 and an outlet port 34 (FIGS. 3 and 4) formed therein, a front cover36 at the drive end of the pump including driving means and seal means,indicated generally at 37, and a rear coverf38 at the antidrive end ofthe pump. The covers 36 and38 are removably secured to the body portion32 by screws 39 extending therethrough and threaded into the centralbody inner end faces of the end plates and receive high pressure workingliquid from a pair of angularly intersecting grooves 56 having theircommon juncture point registering with the discharge zone of the pump.

The particular arrangement and construction of the thrust bearings 51and integral axial pressure loading chamber system, including the mannerin which high pressure working liquid is communicated to the pressureloading chambers, is set out in more detail in my aforementioned UnitedStates Patent No. 2,772,638 and further description thereof isunnecessary for purposes of the present invention. 7 I 1 {It will beapparent that in addition to the axial component of the pump dischargepressure force tending to separate the end plates from the side faces ofthe meshed gears, a radial component of this force is also present andactionable to urge the internal unit assembly toward the low pressureside of the pump casing which introduces aleakage problem around thehigh pressure zone of the pump unless elaborate seals are provided. Thedisplacement of the internal unit assembly toward the low pressure sideof the casing bore also creates a frictional force resulting from theedge contact of the end plates with the housing bore which tends toresist the axial inward counterbalancing force of the axial pressureloading chambers. By the present invention, this displacement of theinternal unit assembly is overcome, as described below, by imposing aradially inwardly directed counterbalancing force at the low pressureorinlet side of the casing bore that is substantially equal in magnitudebut opposite in sense to the displacing radial force at the dischargeside of the internal unit assembly, thereby to maintain the internalunit assembly substantially centralized as a free body in the casingbore.

' The various generated and reaction forces acting on the internal unitassembly 31 as a free body are illustratedv diagrammatically in theforce diagram of FIG. 2. In. FIG. 2, F represents the resultant radiallyinwardly directed component of the discharge pressure force actingat thegears of the internal unit assembly 31. The arrows F represent axialcomponents of the discharge pressure force acting to separate the endplates from the side faces of the gears. The opposed pairs of axiallyinwardly extending arrows R at the ends of each gear shaft 44 and 46represent the axial counterbalancing force exerted by the pressureloading chambers in the thrust bearing means 51 whose summation is equalin magnitude but of opposite sense to the separating forces F The forceF acts on the internal assembly 31 at the high pressure side thereof tourge the latter, as a free body, toward the low pressure side of thecasing bore, this force being conventionally resisted as a bearing load.In the present invention, however, one or more pairs of radialcounterbalancing forces R are provided by the radial pressure balancingchambers on the low pressure side of the casing bore between the edgesof the end plates and the adjacent wall of the casing bore tocounterbalance the displacing force F The forces R are cumulativelyequal in magnitude to the force F but opposite in sense so .that theinternal unit assembly 31 is maintained in a substantially centralizedequilibrium position in the casing as 'a free body.

in somes cases it maybe advantageous to introduce a slight unbalancebetween the displacing and counterbalancing radial force components Fand R, respectively, to thereby maintain the internal unit assemblyurged toward the high pressure or discharge side of the casing bore andthus reduce leakage at this point as well as the necessity for specialseal means between these surfaces.

Referring again to FIG. 1 in conjunction with FIGS. 3 and 4, the radialpressure balancing means of the internal unit assembly 31 comprises apair of annular chambers 57 formed at the low pressure edges of the endplates 49 and disposed substantially centrally thereof. The

pressure balancing chambers 57 are defined "by annular grooves 58 formedin the edge of each end plate and annular seal means in the form ofresilient O-ring seals 59 seated in the grooves 58. The grooves 58 aresufiiciently shallow so that portions of the seals 59 project beyond theedge surfaces of the end plates 49' for engagement with the adjacentinner side wall of the casing bore to form the confined annular chambers57. The eifective areas of the pressure balancing chambers 57 are suchthat the summation of the counterbalancing forces resulting fromconfined high pressure working liqu-id therein, and which is imposed onthe edges of the end plates 49, will substantially counterbalance theradial force component of the discharge pressure force on the oppositeside of the pump.

In order to subject the radial pressure balancing chambers 57 to pumpdischarge pressure and thus provide a counterbalancing force .tocentralize the internal unit assembly 31 in the bore of the casing 30,each end plate 49 includes a pair of intersecting angular bores orpassages .61 that register at one end with the pressure balancingchambers 57 and at their other ends with the high pressure dischargeside of the pump. Thus, the passages 61 extend convergently inwardlytoward the high presisure discharge side of the pump and are intersectedat their juncture point by a longitudinally extending bore 62 whichcommunicates with the discharge pressure zone of the pump adjacent theoutlet port 34 of the pump casing 30. It will be appreciated thatconfined pressurized working fluid inthe radial pressure balancingchambers 57 provides a counterbalancing force to maintain the internalunit assembly 31 in radial equilibrium in the casing 39. "In FIGS. 3 and4, and also in the subsequent illustrated embodiments of the invention,the internal unit assembly is shown displaced completely toward thedischarge side of the casing with the clearances being exaggerated forclarity. However, it is to be understood that the magnitude of thecounterbalancing force may be arranged to provide a substantiallycentral positioning of the assembly or any desired degree of unbalance.

Referring now to FEGS. 5 and 6, a modified radial pressure balancingmeans is illustrated and designated generally at -64, which comprises asecond specific embodiment of the present invention. The pressurebalancing means 64 is illustrated in conjunction with a gear type liquiddisplacement device that is substantially identical in construction andoperation to the liquid displacement device described in FIGS. 1-4.Thus, the present embodiment includes an external casing 66 and aremovable internal unit assembly 67. The internal unit assembly 67includes apair of meshed gears (not shown) that are carried on integraldriving and driven gear shafts 68 and 69. A pair of end plates 71 areprovided for rotatably journalling the shaft portions 68 and 69 of thegears, the end plates 71 and enclosing casing 66 being effective todefine a high pressure zone adjacent the outlet of the device onoperation thereof. A pair of axially extending grooves 73 are providedin the journalling bores 72 which register with the discharge pressurezone and the axial pressure loading chambers of the device to insureadequate lubrication at this point as previously described. The radialpressure balancing means 64 for the internal unit assembly 67 differsfrom the first embodiment of the invention in that the edges of the endplates 71 are each formed with a single vertically elongated rectangularcavity or recess 74 adjacent the inlet side of the pump.

A second circumscribing marginal recess 76, of a somewhat shallowerdepth than the rectangular cavity 74, is provided to receive themarginal edges of a rectangular shaped resilient member 77 whichencloses the cavity 74 and may be made of rubber or other suitableelastomer materials. The marginal edges of the resilient member 77 arebonded or otherwise suitably fastened in the circumscribing recess 76such that the edges of the end plates 71 include what I term a boot typepressure balancing chamber.

it should be understood, however, that the boot type constructionillustrated in FIGS. 5 and 6, which contemplates a sin le resilientmember or strip 77 overlying and marginally fastened to the recess 74 todefine the pressure balancing chamber therebetween, could be modified toinclude a double-walled resilient member construction with pressuresealed perimetrical edges, if desired, to eliminate the necessity ofmarginally connecting the resilient member 77 around the cavity 74. Thelatter construction would in effect provide an innertube typearrangement having certain maintenance and replacement advantages overthe preferred form of construction of the resilient member 77 previouslydescribed.

High pressure liquid is communicated to the pressure balancing cavity 74through a passage 79 which extends transversely through the end plate 71and an axially extending bore 81' that registers with the high pressurezone of the pump. The operation of the radial pressure balancing system64 is in all other respects similar to that of the first embodiment ofthe invention.

Referring now to FIGS. 7-9, a modified radial pressure balancing meansis illustrated which comprises another embodiment of the invention andis shown in conunction with a somewhat different internal unit assemblyhavmg a figure-8 configuration. The general constructron and operationof the liquid displacement device illustrated in FIGS. 7-9 issubstantially the .same as in the two previously described embodimentsof the invention to the extent that it includes a casing 86 and aninternal unit assembly 87 of the type employing axial pressure loadingchambers. The internal unit assembly 87 includes a pair of meshed gears(not shown) that are carried integrally on a driving gear shaft 88 anddriven gear shaft 89. A pair of figure-8 shaped end plates 91 having apair of axial bores 92 therethroughfare provided to journal the gearshafts 38 and 89 and to provide a pumping seal with the side faces ofthe gears. Each end plate also includes a pair of diametrically spacedaxially extending grooves 93 in the journalling bores 92 which registerwith the axial pressure loading chambers in the thrust means of theinternal unit assembly '87 to provide a how path for pressurized workingliquid to lubricate the gear shaft journals 92 as previously described.The position and location of the radial pressure balancing chambers inthe internal unit assembly 87 and the orientation of the flow passagesfor directing working liquid at pump discharge pressure to the pressurebalancing members differs, however, from the previously describedembodiments of the invention as will now be described.

As will be apparent from FIGS. 7 and 8, the radial pressure balancingmeans in this embodiment of the invention comprises a pair of generallysegmental chambers 94 disposed on the low pressure or inlet edges of theend plates 91 and angularly displaced toward the top and bottom ends ofthe internal unit assembly and casing. The angular orientation of thepressure balancing chambers 94 is necessitated by the figure-8construction of the internal unit assembly and easing bore, in that thehigh pressure zone adjacent the outlet of the pump tends to separate thegear shafts 8S and 89 as well as to urge the internal unit assemblytoward the inlet of the pump, which effect is counterbalanced byangularly displacing the radial pressure balancing chambers 94, as shownin FIG. 8. While no specific angular relationship of the pressurebalancing chambers 94 is contemplated, relative to a transverse axisthrough internal unit assembly 87, an included angular range of between15 to 30 for each chamber is preferable. The pressure balancing chambers94 are defined by a pair of rectangular resilient members 95 of rubberor the like having a planar base portion 96 and perimctrical upraisedlips 97 for engagement with the adjoining walls of the casing bore, theresilient members 95 preferably being bonded at their base portions toflattened chordal portions 98 on the end plates 91. The resilientlydeflectable lips 97 project outwardly beyond the plate 91 and arearcuately shaped to conform to and tightly engage the inner walls of thecasing bore in fluid pressure sealed engagement to thus localize theposition and direction of the generated counterbalancing forcecomponent.

Working fluid substantially at pump discharge pressure is supplied tothe pressure balancing chambers 94 through a passage system thatincludes acentrally disposed opening 99 in the base portion as of eachresilient member 95, a radial connecting passage 161 in each end plate91 which registers with an annular groove 102 (FIG.

9) in the side face of each end plate adjacent the gears,

and a pair of radial passages 103 which register with the high pressureor discharge zone of the pump and extend into the grooves Hi2. Thus, itwill be appreciated that high pressure Working fluid is supplied fromthe high pressure or discharge zone of the liquid displacement device ofFIG. 8 to the pressure balancing chambers 94 through a path around theside face of the end plates hi. to augment lubrication of the gear shaftjournal bores. In addition, the angularly offset arrangement of thepressure balancing chambers M is also advantageous to counterbalance theseparating action of this high pressure zone of the pump when a figure-8type internal unit assembly and casing construction is used.

Referring now to FEGS. l-12, another radial pressure balancing means isillustrated in conjunction with a liquid displacement device employingan oval type internal unit assembly 166 which comprises anotherembodiment of the invention. The internal unit assembly 166 includes apair of oval or rounded contour end plates Hi7 having a pair ofangularly displaced pressure balancing chambers 108 disposed on the lowpressure edges of each end plate. The structural details and mode ofoperation of a liquid displacement device employing an oval or roundedcontour internal unit assembly construction is set out in my Patent No.2,848,953, issued August 26, 1958. It will suflice for the purposes ofthe description of the present invention to state that a pair ofseparate longitudinally extending tension members 109 are provided inthe internal unit assembly 196 to resist the reaction forces from theaxial pressure loading chambers. The internal unit assembly 106 is inall other respects substantially identical to the previously describedembodiments and thus comprises a pair of meshed driving and driven gears(not shown) that are carried integrally on gear shafts 111 and 112,respectively, and which are rotatably journalled in bores 113 in eachend plate 167. A pair of axially extending grooves 114 are formed in thejournalling bores 113 to provide fluid communication between the innerside faces of the end plates 107 Within the root circle of the meshedgears and the axial pressure loading chambers of the assembly.

The radial pressure balancing chamber means utilized on the low pressureor inlet side of each end plate 167 is of the direct communication typein that working fluid under pressure is directly supplied through anaxial bore or passage 116 registering with the high pressure zone of thedevice to the common intersection of a pair of diverging passages 117which communicate with the chambers 163. I

The pressure balancing chambers 168 are similar in construction to thepressure balancing chambers 74 illustrated in FIGS. 5 and 6 in that theyare of the inflatable .boot type and have an elongated rectangularshape. As best shown in FIG. l2,'each pressure balancing chamher 168 isdefined by a rectangular shaped cavity or recess 118, formed in the lowpressure edges of the end plates 107, the marginal edge portions of eachcavity 119 having a shoulder or recess 121 therearound to which theperipheral edge portions of a complementary resilient member such as atrip 122 of rubber or the like, is joined to form the pressure balancingchamber 103 therebetween. Working fluid pressure is thus communicatedthrough the connecting passages 117 to the pressure balancing chambers103 to inflate the resilient members 122 into contact with thesurrounding inner Walls of the casing bore to urge the internal unitassembly 106 toward the discharge side of the device.

, It should be understood that while an inflatable boot type pressurebalancing chamber construction has been illustrated and described inconjunction with the end plates 167 of the internal unit assembly 186, aperimetrically upraised lip type resilient member construction couldalso be employed, similar to the resilient members of FIG. 8, if sodesired.

The operation of the pressure balancing means illustrated in FIGS. 10-l2is substantially identical to that described in the previous embodimentsof my invention, particularly the modification illustrated in FIG. 8,and further description thereof is thus deemed unnecessary.

Referring now to FIGS. 13-17, the invention is illustrated in connectionwith another internal unit assembly and casing employing a modifiedfigure-8 type crosssectional configuration and a separate hollow tensionmember construction. The radial pressure balancing means shown in FIGS.13-17 differs somewhat from the previous'embodiments of the invention inthat the pressure balancing chambers thereof are formed in the innerwalls of the casing bore, rather than in the edges of the end plates.

In my aforementioned Patent No. 2,848,953, I have described a similarinternal unit assembly construction employing separate tension memberswhich are axially bored to define passages for communicating workingliquid pressure from the discharge pressure zone of the pump to theaxial pressure loading chamber of the internal unit assembly, to whichreference should be made for the structural details and operation ofthis type of internal unit assembly construction. Inasmuch as thedetails of the construction andoperation of the separate tension memberinternal unit assembly construction and their relationship to the axialpressure loading chamber system form no part of the present invention,only a brief description thereof will be included.

The internal unit assembly and casing construction illustrated in FIGS.13-17 comprises a circular casing 126 having a pair of centrallyintersecting bores 127 129 and 131 that are carried on shafts 132 and133, respectively. Each gear shaft is rotatably journalled in bores 134in separate pairs of lower and upper end plate halves 13d and 137adjacent the side faces of the gears 129 and 131, the end plate halves136 and 137 being flattened along their line of engagement, as at 138,to

maintain their assembled orientation in the casing bore 127. A pair ofdiametrically spaced axial grooves 139 are provided in each journallin-gbore 134 which communicate working liquid pressure from the highpressure zone of the device to the axial pressure loading chambers ofthe internal unit assembly for the purpose and function previouslydescribed. The casing 126 is axially. bored as at 140 and 140' toreceive a pair of longitudinally extending tension members 141 and 142having axial bores 14-3 and 144, respectively, therethrough. The tensionmembers 14-1 and 142 resist the reaction forces of the axial. pressureloading chambers and the bores 143 and 144- provide a'liquid pressurepath to the axial pressure loading chambers and radial pressurebalancing chambers of the device, as will hereinafter be described. I r

The end plate halves 136 and 137 differ from those described in theprevious embodiments in that they are formed with an axial len'gthsuchthat their outer ends will extend somewhat beyond the end faces of theinternal unit assembly casing 126 when their inner side faces are insealed engagement with the side faces of the meshed gears 129 and 13-1.A pair of circular external thrust plates 1% (FIG. 14) are provided forengagement with the projecting ends of the end plate halves 136 and 137and are thus maintained in axially spaced relation to the end faces ofthe internal unit assembly casing 126.

axial witlrand equal in diameter to the bores 140 and 14%, respectively,and a pair of axial counterbores or recesses 148 and 14? formed inthe'outer ends of'the holes 150 and 150', the purpose and functionof-which shall be hereinafter more fully described. A diametrical boreor passage 151 interconnects the counterbores 148 and 14 9, and plugmeans,-indicated generallyat 152, seals the outer end of the passage 151from communication v respective counterbores 143 and 149 so as to defineone pair of axial'pressure loading chambers 155 and 157 therebetween. Itshould be noted that the diameter of V the counterbore 148 and tensionmember .hea'd 153 is substantially greater than the diameter of thecounterbore 149 and tension=meinber head 154, andtnat the counterbore14S and tension member head 153 are eccentric to the longitudinal axisof the tension member 141 in order that the resultant force componentsand moments acting on the internal unit assembly 123 be maintained inequilibrium. Another pair of pressure loading chambers 156 and 157 aredefined in the external thrust plate 146 at the opposite or anti-driveend of the internal unit assembly 128 by means of a pair of annularring-like disc members 158 and 159 mounted at the opposite ends of thetension members 141' and 142, respectively, and seated in close-fittingrelation in i with two pairs of cavities or recesses 167, which areprefthe counterbores 148 and 149; A pair of lock nuts 16d and -1 arethreaded onto the ends of the, tension members 141' and 142 to maintainthe various components of the internal unit assembly 128 and casing 126in assembled relationship. Annular'seal means 162 are disposed aroundthe circumferential edges of the tension member heads 153 and 15 i andthe members 153 and 15 for sealing coaction with the annular side Wallsof the counterbores 148 and 149. Thus, the reaction forces from theaxial pressure loading chambers 156 and 157 at the drive and anti-driveend of the device are transmitted to the shaft portions of the tensionmembers 141 and 142 by the head portions 153 and 154 and annular discmembers 158 and 159 and are thus resisted as tensile stress elongationof the shafts in the manner described and claimed in my aforementionedPatent Nov 2,848,953.

In order to communicate working fluid at pump discharge pressure to thepressure loading chambers 156 and 157 the tension member 141 is providedwith a centrally disposed radial bore v163 (FIGS. 16 and 17) whichcommunicates with the high pressure zone of the device and registerswith the axial bore 143 therethrough. A second pair of axially spacedradial passagesldd and 166 are provided in the tension member 141 andserve to communicate high pressure Working liquid tothe axial pressureloading chambers 156 at the drive and anti-drive ends, respectively, ofthe internal unit assembly 128. The passages 151 serve to direct highpressure liquid to the adjacent pressure loading chambers 157.

Referring particularly to FIGS. 15 and 16 the structural details andoperation of the radial pressure balancing means for the internal unitassembly 128 will now be described. Unlike the preceding embodiments ofthe in-v vention, the radial pressure balancing chambers for theinternal unit assembly 128 are formed in the inner walls of the casingbore 127 at the inlet side thereof and receive high pressure workingliquid through an indirect flow path that includes the working liquidflow path to the axial pressure loading chambers 156 and 157.

As best shown in FIG. 15, thecasing bore 127 is formed erablyrectangular and circumferentially'elongated in shoulder v or recess 168,in the manner previously de-' scribed. IA pair of similarly shapedresilient strip members 16% may be bonded to the shoulders 168 to closethe cavities 167 anddefine a pair of radial pressure balancing chambers170 therebetween. The chambers 17% are thus of the boot type as wereheretofore described in connection with FIG. '6.

In order to communicate working liquid pressure to the pressurebalancing chambers 170, the casing 126 includes a pair of bores 171(FIG. 15) disposed adjacent each set of end plate halves 136-1.7 whichcommunicats with radial bores 172 (FIG. 16) in the tension memher 142for interconnecting each pair of pressure balancing chambers 167 withthe axial bore 144- in the tension member 14 2.

157 atthe drive end of the device is communicated by a passage 174adjacent the head 154 of the tension member 142 to the axial bore 144and thence to the radial pressure balancing chambers 17! by means of thepath previously described. Liquid pressure in the chambers 170 isimparted through the resilient members 169 to the edges of the end platehalves 136-137 for urging the latter toward the discharge side of thedevice in the manner previously explained.

As best shown in FIGS. 16 and 17, the casing 126-is formed with a pairof diametrically disposed recesses 176 and 177 in its circumferentialperiphery around the inlet and discharge ports thereof, respectively, towhich are bonded a complementary pair of channeled, circumferen- Thebores 171 are blind and have theirv open ends closed, as by plug means173. Pressurizing working liquid from the axial pressure loading'chambertially elongated, generally rectangular resilient members 178 havingplanar base portions 179 and radially outwardly extending wall portions181 which form liners for the recesses 176 and 177. The wall portions181 have marginal lips 182 for sealingly engaging the inner walls of anenclosing housing or bore (not shown) in which the internal unitassembly casing 126 may be inserted,

e.g. in a so-called buried installation. The planar base portions 179are formed with openings 183 to permit liquid flow through the inlet anddischarge ports of the casing 126.

Referring now to FIGS. 1825 of the drawings, another modification of theinvention is illustrated which differs from the previously describedembodiments in that it employs an inner tube type resilient memberhaving a pair of radial pressure balancing chambers formed integrallytherein and disposed at opposite edges of each end plate .of theinternal unit assembly. A system of check valves is also provided topermit selective communication of high pressure working liquid to aparticular pair of pressure balancing chambers so that the device canoperate in either direction without structural rearrangement of thevarious'cornponents. This particular modification of the invention alsoemploys a'novel intermediate thrust plate at the anti-drive end oftheinternal unit assembly to provide an auxiliary axial pressureloadingchamber for augmenting the counterbalancing force of the axial pressureloading chambers adjacent the ends of the gear shafts and outer sidefaces of the end plates.

As seen in FIGS. 19, 22 and 23, the embodiment of the inventionillustrated therein comprises a cylindrical internal unit assemblycasing 186 having an elongated bore 187 'therethrough which removablyreceives an internal unit assembly 188 therein. Apair of external.thrust plates 189 are disposed adjacent the outer ends of the internalunit assembly 183 and an intermediate thrust plate 191 is interposedbetween the internal unit assembly and the external thrust plate 189 atthe anti-drive end of the unit. Four separate tension members 192 areutilized to resist the reaction forces from the axial pressureloadingchambers, the tension members being radially symmetricallyarranged and extending longitudinally or axially through the internalunit assembly casing 186.

t The tension members 192 function in a manner similar to the tensionmembers in the previously described embodiment of the invention toaccommodate the reaction forces from axial pressure loading chambersdisposed around the inner faces of the end plates of the internal unitassembly and from the auxiliary pressure loading chamber between theintermediate and external thrust plates at the anti-drive end of theunit, as will hereinafter be more fully described.

As best shown in FlG. 22, the internal unit assembly 188 comprises adrive gear 193 and a meshed driven gear 194, each carried integrally onrespective hollow gear shafts 196 and 197, the driving gear shaft 1%being centrally internally splined, as at 198, to facilitate theapplication of driving torque thereto. The gears 1% and 194 are enclosedby the internal unit assembly casing 186 to define a pair ofdiametrically arranged ports 199 and ceiving working liquid. at A pairof elongated end plates 202 (FIG. 23) are disposed adjacent and engagingthe opposite side faces of the meshed gears, each end plate having alower bore 203 and an upper bore 264 therein constituting bearingjournals for the ends of the gear shafts 196 and 197. The outer sidefaces of the end plates 202 are formed with a pair of annular axiallyoutwardly extending bosses 296 (FIG. 22) which cooperate with acomplemental pair ofcoaxial counterbores 207 and 29% adjacent the endsof the lower and upper gearshafts 196 and 197, the counterbores beingformed in the opposing faces of the adjoining external thrust plate 189at the drive end of the unit and the intermediate thrust plate 191 atthe anti-drive end of the unit. At the driven gear- 1201 (FIGS. 19 and21) for respectively supplying and re- 206, a pair of annular seal rings2G9, and a pair of re-' silient support rings 210. The elements 209 and210 cooperate to provide a compensating seal arrangement more fullydescribed and claimed in my copending application Serial No. 709,045,filed January 15, 1958, now

Patent No. 2,967,487, which should be referred to for a more completeexplanation of this aspect of the structure.

A passage 213 in the thrust plate 139 at the drive end of the internalunit assembly and a passage 214 (FIGS. 24 and 25) in the intermediatethrust plate 191 at the antidrive end of the internal unit assemblyprovide liquid communication between the pressure loading chambers 211and 212. High pressure working liquid is supplied to the axial pressureloading chambers of the device by passages (not shown) in the end plates262. A pair of diametrically spaced axially extending grooves 215 (FIG.

23) are provided in the gear shaft journalling bores 294 and connect thepressure loading chambers 211 and 212 to the high pressure zone of thedevice and contribute to the lubrication .of the journalling bores inaddition to the leakage flow therethrough, as previously described.

The auxiliary axial pressure loading chamber at the anti-drive end oftheinternal unit assembly 138 is indicated at 216 (FIGS. 19 and 22) and isformed between the spaced faces of a central counterbore 217 in theouter face of the intermediate thrust plate 191 and an axially inwardlyextending boss portion 218 on the inner face of the adjacent thrustplate 189. The boss portion 218 includes an annular recess 219 in whichis seated a coil spring 221 that bottoms in the recess 219 and engagesthe base of the counterbore 217 to urge the intermediate thrust plate191 into pressure sealed engagement with the adjacent end plate 202. Theintermediate thrust plate $1 and adjacent end plate 202 are centrallyaxially bored, as at 222, to loosely receive a tubular bushing 223 whichserves to maintain axial alignment of these members and to conductpressurized liquid from the high pressure side of the device to theauxiliary pressure loading chamber 216. v A In order to provideselective liquid communication be- '-tween the bore 222 and the highpressure zone of the device, the end plate 202 at the anti-drive end ofthe device has a pair of diametrically spaced axial bores 224 (FIG. 19)having reduced diameter metering passages 226 at their inner ends whichare in registry with the port passages 199 and 201 of the internal unitassembly 188. Spring biased ball check valves 227 are provided tonormally close the metering passages 226 to provide selectiveunidirectional flow therethrough depending on the direction of rotationof the gears. A pair of angular passages 228 connect the bores 224 withthe bore 222 so that working liquid at pump discharge pressure iscommunicated around and'through the tubular loosely fitting bushing 225to the auxiliary pressure loadingchamber 216. Annular ing chamber 216between the intermediate thrust plate 191 and its external thrust plate189, and a pair of spacedannular seal'means 230 are provided around theperiphery of the tubular bushing 223 to prevent leakage of pressurizedworking liquid between the anti-drive end plate 222 and the intermediatethrust plate 191.

Thus it will be appreciated that the axial pressure loading systememployed in the internal unit assembly 188 is effective tocounterbalance the pressure forces tending to separate the end plates292 from the side faces of the gears 193 and 194, even at extremely highpressure operation, due to the inclusion of the auxiliary axial pressureloading'chamber 216. Moreover, the device is readily reversible withoutrearrangement of the structural components of the device, through theprovision of the spring biased; check valves 227 that insureunidirectional communication of liquid pressure to the auxiliarypressure fromithe axial pressure loading chambers ultimately findsitsway to the hollow interiors of the gear shafts 196 and 197, to bereturned to the low pressure flow of working liquids entering the gearsat the pump inlet.

In orderto regulate the flow of Working liquid from the hollow interiorsof the gear shafts to theum inlet and thus control the flow of liquidthrough the bearings and bearing surfaces of the pump, the externalthrust plate 18!? at the drive end of the pump is provided with i anadjustable bleed means in the form of an adjustable needle valve 231.(FIG. 22) threadedly mounted in an opening 231 in the thrust plate 185and having a bore 232 therethrough and a tapered inner end 233. Thetapered end 233 of the valve member 231 coacts with a valve seat 234 inthe thrust plate 189, which communicates with the hollow interior of thegear shaft 197, to

control the flow through the bore 232. A lock-nut 235 maintains thedesired setting of the needle valve 231 for a given operating condition.The adjustable bleed means is necessitated due to the high sealefficiencies around the pressure loading chambers 211, 212 and 216. l 7

Referring now more particularly to FIGS. 19, 22 and 23, the radialpressure balancing means for maintaining the internal unit assembly 188substantially centralized as a free body in its casing 186 will now bedescribed. As

seen in'FIGS. 19.,and 22, each end plate 292 is formed surroundingone-piece innentube type resilient member @237 having elongated,generally rectangular, confined Each passage 241 is counterbored at itsouter end in the edges of the end'plates 202 to receive a tubular sternpor tion 242 formed on the'inner side face of the resilient member 237thereby providinga liquid pressure sealed passage for directingpressurized working liquid to the interior of the cavities 238. It willbe apparent from the location of the axially extending passages 239 thatone pair of pressure balancing cavities 238 at one side of the devicewill be subjected to pump discharge pressure via one pair of connectingpassages 241 for a given direction of rotation of the gears 193 and 194,and anopposite pair of pressure balancing cavities 238 will be sopressurized on a reversal of the direction of rotation of the gears 193and 194. As previously described, the size, shape and location of thecavities 238 is such as to effectively counterbalance the radialcomponent of the displacing force at the'high pressure side of the pumpeither with a balanced valve 246. The drive end plate 189 includes apair of registering bores 2.47 in alignment with the passages 244.

'formed between the internal unit assembly casing 186 and its enclosinghousing (not shown), such that the latter chamber may be vented to thelow pressure zone of Commu- V nication between the reservoir at thedrive and anti-drive ends of the internal unit assembly casing 186 andits the pump Whenever excessive pressure occurs.

enclosing housing is provided by axial bores 24$ (FIGS.

' 18, 21, 23 and 24) extending through the tension members 192.

In order to prevent leakage around the ports199 and 201 of the internalunit assembly casing 186, a pair of resilient seal assemblies 249 (FIGS.19, 20 and 21) are provided which .are seated in appropriately formedrecesses 251 in the sides of the internal unit assembly casing 186, theseal assemblies 249 being of the same type as the seals 178 illustratedand described in connection with the FIGS. l3l7 embodiment previouslydescribed.

While only certain specific embodiments of my invention have been hereinillustrated and described, it should be understood that modificationsand variations thereof may be effected without departingfrom the scopeof the novel concepts hereindisclosed, as set forth in the appendedclaims.

I claim:

1. In a liquid displacement device of the character described, thecombination of a casing having a bore therethrough, and an internal unitassembly in said casing bore comprising support means, at least oneliquid displace- -With a peripheral edge groove 236 in which is seated.a

ment element rotatably supported by said support means, 7

said element being operable to define separate zones of low and highpressure working liquid in said casing, said high pressure zoneproviding a radial force tending to urge said internal unit assemblytoward the low pressure side ofv said casing, and means for opposingsaid radial force and defining at least one chamber between the supportmeans supporting said element and said casing at the low pressure sideof the latter, said opposing means including a passage providing fluidcommunication between said chamber and said high pressure zone so thathigh pressure working liquid in said chamber provides a force opposingsaid radial forcewhereby to maintain said in-' ternal unit assembly in apredetermined position in said casing bore, said chamber having meansfor confining the high pressure fiuid therein, i

,2. In a liquid displacement device of the character described, thecombination ofa casing having a bore therethrough,'and an internal unitassembly in said casing bore including a pair of meshed gears, a pair ofspaced support means disposed in sealing relation at the faces of saidgears and rotatably supporting the latter, said gears being operable todefine separate zones of low and high pressure working liquid at saidgears, and radial pressure balancing means for opposing the force ofsaid high pressure zone tending to urge said internal unit assembly to-A liquid pressure passage is thus defined from the low 7 pressure zoneof the pump to a reservoir or chamber ward the low pressure side of saidcasing bore, said radial pressure balancing means having at least onechamber disposed between each of said pair of support means and:

resultant counterbalancing force substantially equal and opposite tosaid force at the high pressure zone whereby said internal unit assemblyis substantially centralized in said casing bore.

4. In a liquid displacement device of the character described, thec'ombination of a casing having an inlet and an outlet and a boretherethro'ugh, and an internal unit assembly in said bore comprising apair of meshed gears.

between said inlet and said outlet, a pair of spaced 'end platesrotatably supporting said gears and being disposed in sealing relationat opposite faces of said gears, said gears being operable to definezones of low and highpressure working liquid adjacent said inlet andsaid'outlet,

posing the radial component of the discharge pressure 'force of saidhigh pressure zone, said radial pressure balancing means comprisingflexible means defining a plu .rality of chambers between the peripheraledges of said end plates and said casing at the inlet side of thelatter,

said flexible means being constructed and arranged to confine highpressure working liquid in said chambers, said balancing means includingpassages interconnecting said chambers With said high pressure zonewhereby high pressure working liquid in said chambers opposes saidradial component to maintain said internal unit assembly in apredetermined position in said casing bore.

5. In a liquid displacement device of the character described, thecombination of a casing member having an inlet and an outlet and a boretherethrough, and an internal unit assembly in said casing borecomprising a pair of meshed gears between said inlet and said outlet, apair of spaced end plate members rotatably supporting said gears andbeing disposed in sealing relation at opposite faces of said gears, saidgears being operable to define zones of low and high pressure workingliquid adjacent said inlet and said outlet, respectively, and radialpressure balancing means for opposing the radial component of the highpressure force in said high pressure zone, said radial pressurebalancing means comprising a resilient seal interposed between andengaging the peripheral surfaces of said end plate and casingmembers todefine with at least one of said peripheral surfaces chambers-forconfining high pressure working liquid, said balancing means includingpassages interconnecting said chambers with said high pressure zonewhereby to maintain said internal unit assembly in a predeterminedposition in said casing bore.

6. The combination-according to claim 5, in which said chambers aresurrounded by annular recesses formed in the low pressure side of one ofsaid members, and

annular resilient seals are seated in said recesses and have portionsthereof engaging the adjacent wall of the other of said members inpressure sealed relationhip.

7. The combination according to claim 5, in which said chambers aredefined by flattened portions on the peripheral surfaces of said endplates and segmentally shaped resilient seals carried on said portions,said resilient seals having a lip therearound for engaging said Wall inpressure sealed relationship, said lip including arcua tely shapedportions to conform to the adjacent wall of said casing bore. 1

8. In a liquid displacement device of the character described, thecombination of a casing having an inlet and an outlet and abore'therethrough, a pair of meshed gears 1 in said casing between saidinlet and said outlet, a pair of spaced end plates rotatably supportingsaid gears and being disposed in sealing relation at. opposite faces ofsaid gears,'saidgears being operable to define zones of low and highpressure working liquid adjacent said inlet and said outlet,respectively, and radial pressure balancing means for opposing theradial component of the high pressure force in said high pressure zone,said radial pressure balancing means-comprising at least one elongatedresilient member peripherally bonded to the edge of each end plate atthe inlet side thereof to define a chamber therebetween, said balancingmeans including passagesv interconnecting said chambers with said highpressure respectively, and radial pressure balancing means for op- 16maintain the gears and end plates in a predetermined position in saidcasing bore; a r

9. The combination according to claim 8, in which said resilient membercomprises a single elongated strip of resilient material extendingsubstantially across the full.

described, the combination-of a casing having an inlet and an outlet anda bore therethrough, a pair of meshed gears in said casing between saidinlet and said outlet, a pair of spaced end plates rotatably supportingsaid gears and disposed in sealing relation at opposite faces of saidgears, said casing bore having atleast one cavity formed in the wall ofsaid bore adjacent the-edges of said end plates on the inlet sidethereof, said gears being operable to define zones of low and highpressure working liquid adjacent said inlet and said outlet,respectively, and radial pressure balancing means for counterbalancingthe radial component of the high pressure force in said high pressurezone, said radial pressure balancing means comprising resilient meansdefining at least one chamber between the peripheral edge of each endplate and said casing at the inlet side of the latter, said resilientmeans being an elongated strip of resilient material peripherally bondedaround the edge of its associated cavity, said balancing means includingpassages interconnecting said chambers with said high pressure zonewhereby high pressureworking liquid in said chambers provides a forceopposing said radialcomponent to maintain the gears and end plates in apredetermined position in said casing bore.

let, a pair of spaced end plates rotatably supporting said gears andbeing disposed insealingIrelation at opposite ,faces of said-gears,:eachof'said end plates having a shallow recess formed in each of the side.edges thereof,

said gears being operable to define zones of low and high pressureworking liquid adjacent said reversible inlet and outlet dependent uponthe direction of rotation thereof, and radial pressure balancing meansfor opposing the radial component of the high pressure force in saidhigh pressure zone, said radialpressure balancing means comprisingresilient means defining a pair of chambers between therespective sideedges of each end plate and said casing at the. inlet and outlet sides,said resilient means being a strip of resilient material seated in eachof said recesses and having pockets formed therein at the edges of saidend plates, said balancing means including passages selectivelyinterconnecting the pockets opposite a high pressure zone With highpressure liquid, depending upon the direction of rotation of said gears,whereby high pressure working liquid in said pockets provides a forceopposing said radial component to maintain the gears and zone, saidresilient member being expansible in response to confined high pressureWorking liquid communicated to said chamber to engage the adjacent wallof said casing bore, whereby high pressure working liquid in saidchambers provides a force opposing said radial component to end platesin a predetermined position in said casing bore.

14. The combination according to claim 13, in which each of said endplates has a shallow recess extending around the periphery of the endplate, and said resilient means is seated in said recess and extendsaround the end plate. 7

References Cited in the file of this patent UNITED STATES PATENTS1,880,108 Ross Sept. 27, 1932 (Other references on following page)Banker Feb. 25, 1958 18 Ilune June 3, 1958 Hilton July 8, 1958 NagelyAug. 26, 1958 Aspelin Sept. 30, 1958 Hodgson Feb. 2, 1960 Lorenz Feb. 2,1960 Booth et a1 Apr. 12, 1960 FOREIGN PATENTS Austria Sept. 25, 1959Great Britain Sept. 11, 1957 Germany Apr. 18, 1957 Germany Apr. 16, 1959

